388. The longest absolute path to the file

388. The longest absolute path to the file

Answer key

subject ： Give you a string dir\n\tsubdir1\n\t\tfile1.ext\n\t\tsubsubdir1\n\tsubdir2\n\t\tsubsubdir2\n\t\t\tfile2.ext
It represents a directory

dir
* subdir1
* * file1.ext
* * subsubdir1
* subdir2
* * subsubdir2
* * * file2.ext

How long is the longest path in the directory

dir/subdir2/subsubdir2/file2.ext   return 32

Ideas ：

1. The length of the upper level directory name at the same depth is the same 
2. Record the upper level directory name , use map save 
3.\t The number of is the depth 
4.\t To \n Between them is the directory or file name 
5. Traversal string , Traverse while saving map

Code

func lengthLongestPath(input string) int {
    
	//route key-> depth  val-> The length of the directory 
	route, n, ans := make(map[int]int), len(input), 0
	for i := 0; i < n; i++ {
    
		isFile, depth, cnt := false, 0, 0
		// Detect the depth of the current name 
		for ; i < n && input[i] == '\t'; i++ {
    
			depth++
		}
		// Check the length of the current name 
		for ; i < n && input[i] != '\n'; i++ {
    
			if input[i] == '.' {
    
				isFile = true
			}
			cnt++
		}
		// Storage map
		route[depth] = cnt
		sum := 0
		// If it's a file 
		if isFile {
    
			// Count the length of absolute path 
			for j := 0; j <= depth; j++ {
    
				sum += route[j]
			}
			//sum+depth  Add depth The reason is the absolute path :a/b.txt Medium /
			ans = max(ans, sum+depth)
		}
	}
	return ans
}
func max(i, j int) int {
    
	if i > j {
    
		return i
	}
	return j
}